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FIRST QUARTER 1996 <br /> PROJECT STATUS AND MONITORING REPORT <br /> USA STATION#110 - STOCKTON <br /> 3.1 Groundwater Flow and Gradient <br /> Groundwater data collected at the site indicates that the depths to groundwater range from <br /> 70 03-feet to 71 23-feet below ground surface (bgs) The corresponding groundwater elevations <br /> range from 44 62-feet below mean sea level (MSL) to 45 62-feet below MSL Groundwater <br /> elevation contours constructed from the January 18, 1996 gauging activities indicate groundwater <br /> is flowing to the northeast at a hydraulic gradient of approximately 0 0039-feet/feet A review of <br />' the historical field data suggests that the groundwater generally flows to the northeast with minor <br /> fluctuations to the north and south, shown on Figures 4 and 5 <br />' 3.2 Results of Groundwater Laboratory Analyses <br />' TPH G was detected only in monitoring wells MW-2-P and MW-3-P at 780 and 170 micrograms <br /> per liter (ug/l), respectively TPH G was non-detect at the laboratory analytical detection limit in <br /> all other monitonng wells TPH D and organic lead were also non-detect at the laboratory <br />' analytical detection limits in all the wells sampled during this quarter Analytical results are <br /> summarized in Table 3 and shown on Figure 6 Copies of laboratory reports and COC <br /> documentation are provided in Appendix B <br /> 3.3 Conclusions <br /> A review of the groundwater monitoring results suggests that TPH impacted groundwater is not <br /> present in the off-site wells The wells with detectable hydrocarbon concentrations are MW-2-P <br /> and MW-3-P, which are in close proximity to the on-site underground fuel tanks and dispenser <br /> ' islands These wells are also located on the upgradient side of the site If the source of TPH <br /> compounds is on-site, the impacted groundwater does not appear to have migrated significantly <br /> from the source Park recommends that one addAional round of quarterly groundwater <br /> ' monitoring be conducted (April, 1996) to evaluate any trends in the dissolved hydrocarbon plume <br /> beneath the site Based on the results of the proposed groundwater monitoring, the need for <br /> remedial action at the site can be better addressed <br /> 1 <br /> 1 <br /> • 3 <br /> 1 <br />